There is a half century of history of schemes which have been implemented for improving the efficiency of elevators. Among these are ways of determining which car shall answer a hall call, such as the relative system response dispatchers disclosed in U.S. Pat. Nos. 4,363,381, 4,815,568, to Bittar, and 5,024,295. Others involve peak period dispatching, including zoning and channeling, some of which is disclosed in U.S. Pat. Nos. 4,792,019 and 4,838,384. And, to improve further on such systems, various forms of traffic prediction estimates have been used, such as in U.S. Pat. No. 5,022,497. The systems become more sophisticated with techniques which have been variously referred to as artificial intelligence, fuzzy logic and so forth. All of the foregoing relate to efficient operation of the elevators within a group.
To achieve more efficient operation of tall buildings (in excess of, say, 20 floors) buildings have been provided with groups of elevators, one group operable only in the lowermost floors, and the other group operable only in the highest floors of the building, in which case the groups are referred to as the "low rise" and the "high rise". In the aforementioned parent application, swing cars that can serve a low rise and a high rise (or low and medium, medium and high) are selectively assigned to the group controller related to that rise (low or high) having the highest traffic burden, on an every cycle basis with the possibility, and real likelihood, of assigning each swing car to a different group each time that it completes a trip. That system takes advantage of the precept that regardless of the floors at which persons enter an elevator, they are not concerned with which lobby service corridor they are delivered to, and therefore can be delivered to the lobby service corridor of a group other than the group under the control of which the passengers entered the car at floors above the lobby. In that system, elevator cars which are located within the lobby service corridor dedicated solely to one group (e.g., low rise) are also located in the lobby service corridor dedicated solely to a second group (e.g., high rise). Such an elevator swing car has doors on two sides operable to allow passage of passengers between the car and either one of two such distinct lobby service corridors which are opened to the lobby service corridor associated with the set of floors to which it has been assigned for its next run as it approaches the lobby floor at the conclusion of a current run, without regard to the set of floors to which it had been assigned during the current run. In normal operation, each swing car is assigned to a group controller related to one set of floors each time that the swing car concludes a run and approaches the lobby floor. In any cycle when an elevator is being assigned, it can be assigned to one of the groups and help that group out. Within minutes, either itself or a companion swing car can be assigned to the other group to help that group out. Within minutes it can be reassigned to the second group or it can be assigned back to the first group, the point being that no fancy determination has to be made because the determination can be reversed on a cyclic, per-run basis. Once an elevator is assigned to a group, it simply is added into the logic for that group and can be handled in the same fashion as any other elevator in that group.
In the system of the parent application, the assignment to one elevator rise group or the other (which herein are taken to be a low rise and a high rise) is made only as it approaches the lobby floor at the completion of each run. If a car exhausts its demand (having no hall calls or car calls) it must return to the lobby only to determine whether it should be assigned to the high rise or the low rise, regardless of how heavy the traffic level may be, and regardless of whether the greatest demand is at the lobby or on the upper floors. This is wasteful in other than up peak periods. Similarly, that system does not permit a car assigned to the low rise to keep traveling upward and respond to hall calls in the high rise. Whenever a car in the high rise is returned to the lobby with an extremely light load (such as late in the evening, in an office building) it loses the opportunity to pick up one or two passengers on the way down. Of course, there is no point to having a high rise and a low rise if every elevator serves both rises; this is simply a reversion to the ancient single rise system which would be totally disastrous in very tall buildings.